2003 trailblazer unsolved issue

[Eric2777]

My 2003 trailblazer is having issues running when I put it in gear and accelerate I have replaced the motor,fuel pump,fuel filter,cam sensor,cleaned the throttle body,and computer. Will start and run in park just fine put it in gear will then go and stumble and stall. When I replaced the computer I was able to drive it for 44 miles and the issue started again. I cycle the key and I can't hear the fuel pump and it won't start. I then let it sit for short period of time then cycle the key and the fuel pump will work then I put it in gear and try to accelerate and it dies. I have checked the fuse box and switched the relay and it seems it has power. The fuel pressure regulator has no gas in the vent line. Any ideas I am at a dead end and have no more ideas

 

[Mounce]

Have you checked the grounds for the fuel pump? How about the harness junctions for the fuel pump that are a rare but known failure?

When you looked at the fuse box did you dismantle it and inspect the wiring for the fuel pump circuit?

 

[Mooseman]

If you jump the relay socket to make the fuel pump work, does it run and drive? If you still don't hear the fuel pump and there is power as per the schematics at the relay and fuse (download the manuals from the link in my signature), then there is a wiring issue from the fuse block to the pump, a bad ground or the pump is bad (even new pumps can be bad).

 

[Kelly@PCMofNC]

Also does it happen to have any codes stored/pending?

 

[mrrsm]

As per @Mooseman 's suggestion in Post #3:

These three Videos may be of some help:

No Crank No Start (Has information on the Relays & Fuses for the Ignition System)

Cranks... But Will NOT Start... as per Post #4 ...CHECKED CODES?

How to Test the Fuel Pump Circuits & Relay...